Once you have candled a rotten egg and know what to look for, you will know . It ends up looking like a dark soupy mess that can freely roll around as you move the egg. You will almost never see any remaining signs of veins.BTW, what does an egg look like that's spoiling? Can you tell by candling? Or is it generally just a big, staaainky surprise? All these looked like fresh eggs, except for two that appeared to have the earliest stages of visible development.